An LDO regulator is a direct current (DC) linear voltage regulator that can operate with a very low dropout, where “dropout” (also termed “dropout voltage”) means the difference between the input voltage (e.g., received power supply rail voltage) and the regulated out voltage. As known in the conventional voltage regulator arts, low dropout voltage may provide, for example, higher efficiency and concomitant reduction in heat generation, and may provide for lower minimum operating voltage.
Two of the performance metrics for LDO regulators are the capability to avoid voltage drop, or “droop” in response to rapid load increase, and stability against oscillation. Conventional LDO regulators, though, are feedback devices. Therefore, as can be inherent in feedback devices, conventional design techniques directed to improving one of these two LDO regulator performance metrics may have opposite effects on the other. A completed conventional design of an LDO regulator may, therefore, reflect a compromise. One result of such conventional design compromise can be reduction in a maximum current capability, or current change, that the LDO regulator can handle while maintaining an acceptable droop. In addition, the compromise is embodied in fixed device parameters, for example fixed bias current and compensation components. However, operating conditions are not necessarily fixed. For example, LDO regulator output current may vary over a large range. One set of bias current or component values may be unable to provide optimal droop, or stability performance, or either, over the entirety of such a range.